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Be and Al exhibit diagonal relationship....

Be and Al exhibit diagonal relationship. Which of the following statements about them are not true ?
I. Both react with HCl to liberate `H_(2)`
II. They are made passive by `HNO_(3)`
III. Their carbibes give acetylene on treatment with water
IV. Their oxides are amphoteric

A

a) III and IV

B

b) I and III

C

c) I only

D

d) III only

Text Solution

Verified by Experts

The correct Answer is:
D
(i) Be and Al both react with HCl to liberate `H_(2)`.
`Be + 2HCl rarr BeCl_(2) + H_(2) uarr`
`2Al + 6HCl rarr 2AlCl_(3) + 3H_(2) uarr`
(ii) Be renders passive with conc. `HNO_(3)` and so does not react. Conc. `HNO_(3)` is strong oxidising agent and forms very thin layer of oxide on the surface of metal. Similarly, Al become passive in conc. `HNO_(3)` due to formation of oxide layer on the surface.
(iii) Their carbides gives methane on treatment with water.
`Be_(2)C + 4H_(2)O rarr 2Be(OH_(2)) + CH_(4)`
`Al_(4)C_(3) + 12H_(2)O rarr 4Al(OH)_(3) + 3CH_(4)`
(iv) Their oxides, BeO and `Al_(2)O_(3)` are amphoteric.
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